"He's pretty sore," coach Andy Reid said Monday. "He's going to try and battle through it. He'll struggle to practice. He's going to do everything he possibly can to try to play. We'll see how that goes. He's staying optimistic about that."
McNabb is not ruling himself out for the Eagles' game against New Orleans next Sunday.
"Not necessarily, anything can happen. It's just Monday right now, but if Friday and Saturday come along and I'm feeling a lot better, you just never know," he said. "It's a slow process of just meeting with our trainers, doing two-a-days with treatment, going through the process of just like I'm playing in the game, and seeing how I feel at the end (of the week)."
Third-year pro Kevin Kolb filled in for McNabb during Philadelphia's 38-10 victory over Carolina in the season opener. He would start against the Saints if McNabb can't play.
Michael Vick is not eligible because he was suspended for the first two regular-season games as the last part of the NFL's penalty for his role in a dogfighting ring. Vick probably wouldn't start even if he could play because he's still rusty and Reid has maintained all along that Kolb is the backup.
Kolb hasn't moved the offense much in the few opportunities he's had, though he's never worked with the starters during a practice week. The Eagles could find themselves in a shootout against Drew Brees and the rest of New Orleans' high-octane offense, so they can't afford a slow start.
"I have full confidence in him," Reid said of Kolb. "I don't worry about his accuracy or knowledge of the offense right now. It's just a matter of getting caught up with the game speed of the regular season."
The Eagles don't have a fourth QB on their roster, so they'll need someone to back up Kolb if McNabb can't play. A.J. Feeley, who was 4-3 filling in for McNabb in 2002 and 2007, is a logical choice to be re-signed. Feeley was released on Sept. 6.
"We have a lot of respect for A.J. but I know other people in this league do, too," Reid said.
McNabb got hurt when he took a hard shot on a 3-yard TD run in the third quarter. He spun away from a defender at the goal line, but was nailed by Panthers nose tackle Damione Lewis on the ground in the end zone.
"I can't say anything on that," Reid said. "You get those 300-plus pound guys motoring and it's hard to stop. Sometimes they come in a little bit late."
The NFL reviewed the play and ruled the hit was "not illegal," spokesman Greg Aiello said in an e-mail.
"It's a rough game. We're not clamoring about Josh McCown. I mean he got whacked pretty good, too," Panthers coach John Fox said after reviewing the tape. "It's tough. I'm sorry he got hurt. I don't ever like to see any player get hurt, our team or theirs. It's unfortunate."
McNabb played an injury-free season last year for the first time since leading the Eagles to the Super Bowl in 2004. He's missed 24 games, including playoffs, due to injuries during his first 10 seasons in the NFL. The Eagles are 14-10 in those contests.
Reid said McNabb doesn't have to practice to play this week.
"We've seen him do that before and play some pretty good games," Reid said. "We'll take it day by day. We just want to get him back healthy."
Reid isn't concerned that McNabb could exacerbate the injury by playing.
"It's broken. I don't think you can make that part worse," Reid said. "We just have to see how he can function. I'm not going to put him out there if he can't function.
"Rib injuries are all different. This one's displaced a little bit and pretty painful. I know other guys have played with broken ribs. They're all different. It's hard to compare."
If it's simply a matter of pain tolerance, as often is the case with broken ribs, McNabb proved a long time ago he's a tough guy. He broke his right ankle in the first quarter against Arizona on Nov. 17, 2002, stayed in and threw four touchdown passes. McNabb missed the next six games, but returned for the playoffs.
He sat out the final seven games in 2005 with a sports hernia and a torn ACL cost him the last eight games in '06, including the playoffs. McNabb didn't play two games in 2007 because of ankle and thumb injuries.
"Donovan is resilient," teammate Brian Westbrook said.
AP sports writer Mike Cranston in Charlotte contributed to this report.